A widely used tool used by medical professionals for performing relative simple diagnostic tasks is the stethoscope, which is used to listen to a variety of internal body functions through the skin of a human. The conventional stethoscope is to some extent nowadays substituted by an electronic digital stethoscope which amplifies the sound captured.
The discovery of murmurs or low level noise from the coronary arteries with stenotic plaque of the beating heart was done in the 1970'ies. The plaque leads to change of the circulating blood from a laminar situation to turbulent streaming. The turbulence will lead to vibrations that may be picked up at the skin surface as sounds. In spite of the early discovery, the use of the level of intensity of the murmurs has never gained commercial impact, probably due to major challenges to make effective algorithms for the management of the sound recordings. The intensity is 100 to 1000 times less than the normal heart beat and cannot be heard by the normal ear with the stethoscope and the requirements to proper recordings are extreme. This means that any detail associated to the recording and the data management must be reconsidered for optimization or finding new solutions.
In WO-2009/080040-A1 and in WO-2010/078168-A2 a number of such aspects have been addressed. WO-2009/080040-A1 describes adhesive patches used for monitoring of acoustic signals. To enhance the quality of the recordings, the acoustic conductivity, transmission and contact between conducting means and skin surface is optimized by maintaining the pressure between the converting means and the skin surface as stable as possible. WO-2010/078168-A2 discloses an acoustic sensor assembly comprising an acoustic sensor intended to provide accurate and robust measurements of bodily sound under a variety of conditions.
In addition the following documents related topics are addressed.
US-2009/0099479 relates to an apparatus and method for determining proper endotracheal placement.
US-2008/0228095 relates to a portable viewable and audible stethoscope for visually and audibly monitoring the vital life signs of a patient.
And in U.S. Pat. No. 5,737,429 there is disclosed a multi-functional, hand-held medical device for measuring bodily functions and physiological parameters and for medical screening and diagnosis by dual sound detection.
From this point of view there is still a need for further development in the field to reach a full solution for the delicate recording of acoustic heart sounds. New equipment and methods should be developed to overcome still important issues for acquiring the best possible high quality recordings and the appropriate subsequent management thereof.
The object of the present invention is thus to provide an improved system for the recording of acoustic heart sounds.